Manufacture of incandescent electric lamps and similar articles



May' 1, 1923.

E. MITCHELL ET AL MANUFACTURE OF INCANDESCENT ELECTRIC LAMPS AND SIMILAR ARTICLES Filed Aug. 3. .1920

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A JAZYEH TUBE. 13052-5 Evmrmr Mz'c'HEZ/rl, .Akzzzawa ZZIHME'E' III/212m,

H Patented May 1," 1 9 23.. v

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"LORI-S nnwm iiIrqnnLL AND ARTHUR amns'wnnrn, or cnnvnmun, omo. ASSIGNOBS 'ro GENERAL ELECTRIC COMPANY, A connonarmu on NEW:

YORK.

' nimuracrunn or mcaunnscnur ELECTRIC 'Lmrs sriunna narrows.

Application fil ed August a, 1920. Serial No. 400,937.

Ohio, have invented certain new and useful Improvements inthe Manufacture of Incandescent Electric Lamps and .SimilarArticles, ofwhich the following is a specifica- 10 tion.

- Our invention relates to incandescent elec-- tric lamps and more particularly to tlpless' incandescent electric lamps. This application is a continuation of our applications Serial No. 283,801, filed March 20, 1919 entitled -Tipless incandescentdamps and similar articles and Serial"No..292,464, filed April 24, 1919, entitled Sealingin machine. A In the manufacture of ordinary moandescent lamps, the bulb is perforated atthe larger end and a tube is sealed over theperforation so as to allow subsequent exhaust, of the air from the bulb; The step of at taching this tube is called tubulating,, The tip is 'a: pointed projection which remains after the aforesaid tube has been fused off to close the opening in the bulb'after the exhausting operation is completed. Beyond 30 functioning as a closure, thetip is not. useful but, on the other hand, is objectionable not only because it is unsightly, but also because it obstructs the transmission of light from the lamp. In some types of lamps. such as those made from opal or colored glass, tubulating and sealing off injure the color around the tip.

Many attempts have been made to eliminate the tip but none of them hasresulted in an flective commercial method of its accomplishment. In some cases it has been attempted to attach the exhaust tube to the bulb neck. One of the objections to this method is that it produces a lamp whichis centage of breakage. Difliculty is also-e\'- Y perienced in attaching the base to such a lamp. According to'our invention, as set forth in our application Serial No. 283,801,- the exhaust tube is attached to the stem tube the mass of fused glass which is formed around the inner end of the exhaust tube during the operation of sealing-in the leaddifiicult to'handle and causes a high per-.

mercial success for the reason that the aperture through which the exhaust tube has been connected with the interior of thefbulb' has not beenproperly disposed nor have the methods of its formation been efiicient in preventing strain in the glass and in'avoiding injury to the mounting for the leadingin wires and other parts of the lamps. Moreover, certain of these rior methods have been incapable of appllca-tion to the metal filament lamp which comprises a filament supporting rod fused to the top of the stem tube. It is also the fact that prior methods for producing tipless lamps have been essen- 'tially hand methods and have not lent themselves to the use of labor saving machinery. According to our methoddisclosed in our application Serial No. 283,801, the exhaust .tube is joined to the stem tube at the inner end thereof. In this specification, the ex pression inner end is used with reference to the stem to indicate that end of the said tube to which the filamentsupport is at-' tached and'in which the leading-in wires are sealed, while the expression outer end" indicates the end which is united to the bulb. The corresponding ends of the exhaust tube are similarly designated. .The aperture or passage through which the exhaust tube communicates with the interior of the bulb is preferably lateral or transverse with reference to the stem tube and thus allows the mounting of a filament supporting rod at" the top of the stem. Such passage is preferably formed by applying air pressure to ing-in wires and immediately thereafter.

The customary method of sealing-in these leading-in wires is to extend them through the stem tube, to fuse the inner end of the stem tube, and to compress by clamping the fused glass around the said wires. This re- ;sults in a flat, solid mass ofglassat the in ner end of the stem tube. When this method 9 is applied in connection with our invention,

the 'inner end of the exhaust tube is fused at the same time as the inner end of the stem tube and is clamped'with the'la'tter. Air pressure is applied'through the exhaust tube and, preferably, additional heat is supplied to thoroughly fuse the glass around the inner end of the exhaust tube, and this causes v point of least'resistanc'e, which passage isat the mass glass to swell and become bulb= shaped. As the airpressure is COIltlIlllBd," a

passage is'blown through the glass at the an angle to the flat Surface ofthe clamped. portion and usually substantially normal thereto; Inasmuch as theplane of the leading-in wires is in tl;ie "direction of 'the flat "during the fusing and clamping operationso as to prevent, to a certain extent, the collapse .of the walls of theexhausttube. This will cause the passage to bela-ter blow'n at a point closer than otherwise to the inner end of the seal. In most cases, however, this supplemental blowing operation is unnecessary.

The pressure of the air supplied through the exhaust tube should be sufficiently low to prevent too quick'a blow out and to allow a gradual spreading of the glass to form a bulb-shaped thin-walled ratherthan a narrow thick-walled orifice or passage. The low pressure accomplishes this by keeping the exhaust tube against the stem tube thus securing a thorough fusing of the glass which is then blown thin until,it blows out at some point to form an aperture. The amount of pressure is a matter which canbe determined by trial. It has been-found in certain cases that when too great a pressure was applied, a narrow passage and smallaperture resulted probably due to imperfect fusion of the glass. In our application Serial No. 283,801 -we have set forth specifically a pressure'which we have found suitable for stems to be used in 75-watt lamps and also a convenient means for gauging this 'pressure.

Various other advantages and features of the method of our invention will appear from the detailed description which is given in our application Serial No. 283,801 and from a reference 'to the drawing which accompanies that application.

In our application Serial. No. 292,464,filed I April 24, 1919, and entitled Sealing-in machine, we have disclosed a machine for sealing into a lamp bulb a stem made according to the method of our invention disclosed in our application Serial "N0. 283.801.

I The sealing-in machine embodying our invention enables us to, accurately position the filament with respect to the lamp bulb as explained messes injfhat application. Hereto'fore in theproe f; sealing-in an ordinary mountfpoma stem tube, leading-1n 'wires'ifand filament or stemfiiube, leading-1n w1res',-supfi lament, 1t was necessary forport rod andthe-operator the seallng-in machine to center the filament in the lamp bulblafter theimount was sealed in and while the glass of the sealed region was still plastic. This not only required -care and. skill inv an extra step but was possible only with clear glass bulbs or bulbs through which the operator could see. Thus it was practically impossible as well as expensive to try to produce a lamp having a bulb of translucent glass.

However, we are able to produce with 7 equal success clear glass bulbs and translucent or colored glass bulb lamps with accurately centered light sources by producing a lamp mount with analigned exhaust tube attached thereto through the method of our invention disclosed in our application Serial. No. 283,801 and ..uniting the lamp mount, positioned by means of the exhaust tube, to a lamp bulb by means of the scaling- .in machine embodying our invention as dis closed in our application Serial No. 292,464.

Fig. 1 is an elevation showing the way in which the partsv of the stem are preliminarily assembled according to our invention;

Fig 2 is a front elevation of the finished stem made according to our invention; Fig.

-3 is an elevation partially in section of a lamp made according to our invention, the section ,bemg 1n a plane normal to that of- Fig. 2: Fig. 4 is a fragmentary top plan view of a sealing-in machine; Fig. 5 is ,an

elevation partially in section showinga tip.-

less lamp after the sealing-in operation been performed: Fig. '6 is a fragmentary elevation partially in section of a rotatable head of the sealing-in machine: and Fig.7 is a sectional elevation of the baflle tube-with the mount support tube shown in dotted lines in cross-section in operative position with respect to the baffle tube.

Referring now to the Figs. 1. 2 and 3 in the drawing. the stem tube 1. exhaust tube 2, the leading-in wires 3 and the filament sup port rod 4 are assembled as shown in Fig. 1 with the exhaust tube between the leading-in wires and the inner end thereof subs'tantiallv in line with the inner end of the s em tube, the exhaust tube being substantially aligned with the stem tube. In types of lamps requiring a filament support rod the latter is included as shown, with its end substantially abutting against the end of the exhaust tube so as to allowall the parts be desirable to introduce air pressure through the exhaust tube 2' to overcome, to a certain extent, the tendency of the walls to collapse. In any event, air pressure is introduced after the clamping operation and it is preferable to taneously apply heat adjacent to the clamped portion. This results in a formation of the stem such as shown in Fig. 2 in which the end of the exhaust tube 2 merges into that of the stem tube 1 and in which a substantially bulb-shaped portion 5 is formed communicating by a passage or aperture 6 with the interior of the lamp bulb.

After the formation of the stem, as shown in Fig. 2, a filamentary light source ported by the anchors 8 fastened in the sup-. port rod 4 is connected to the leading-in wires?) and a mica-heat deflector 9- attached for support to the which is done according tice in lamp factories. The stem with the addition of the light source 7 as shown. in Fig. 6 is called a mount.

In Fig. 4 is shown a sealing-in machine of the general type disclosed in Patent'No. 1,011 523 granted to A. Swan, December 12, 1911. The 'bed '10 of the machine has mounted thereon a rotatable frame 11 carrying a number of rotatable heads 12 which carry the lamp parts during the operation of sealing-in.

The assembly of lamp parts in a rotatable head is shown in Fig. 6. The rotatable .head comprises a base 13 having mounted thereon two upright supports 14 which carry on their upper ends the bulb support 15. Through the center of the base 13 passes the main support tube 16'which carries at its upper end, by means of the collar 17 the mount support tube 18 and thebafile tube 19. The mount support tube is closed at to the usual praci one end and has two diametrically disposed lateral openings 20 near this end for the reception of the blocks 21 on the end of the similar spring fingers 22 attached to the collar 17 diametrically opposite each other. The blocks 21 serve to align the mount support tube 18 and the baffle tube 19 and serve also to align the exhaust tube 2 of the mount as more fullv described hereinafter. Above the openings narrow lateral openings 22', two of whichare shown in Fig. 7, for the admission'ot the air into the mount support 'tube. Just below the open end is a shoulder 23 which serves as a rest for the stem 1 offthe mount and below the shoulder is an annular series of lateral openings 25 through which air is emitted to blow off the :fused surplus neck of the lamp bulb. Some airmay be emitted at the top of the mount support tube and pass between preliminarily and simul 7 sup- I leading-in wires; all of 20 are three long,

the shoulder and stem tube to assist in the blowing off opera- '16. The inside of the tube is divided into an upper chamber 26 and a lower chamber 27 by the bafile 28 having an opening there through of substantially the same diameter as the mount support tube. This bafile is provided with two channels 29 which afford a passage for the air through the said bafile. Two diametricallyopposite lateral openings 30 extend through the reception of the scribed.

The main support tube'16has a beveled cupped opening in the upper end to direct the air toward the channels. The lower end is threaded for the reception of the nuts 31 blocks 21'heretofore dewhich hold thev circular gripping disc 32 in place. The tube 16 is held in the base 13 and extension 33 by friction and may be raised orlowered as by pressing up or down respectively on the may be rotated by means of a gear 34 attached to the extension 33.

The spindle parts are assembled as shown the tube-and battle for disc 32. The head 12 in Fig. 6, the main support tube first being 1 placed in. the base 13 and the collar 17 lipped on and fastened to th main supp? 106 tube. The mount support tube is then msertedin the baffle tube and the latter placed over the'main support tube and substantially resting .on the collar 17 with the openinggf20 of the mount support tube registering with the openings 30 and with the blocks 21 on the end of the spring fingers 22 inserted therein. The exhaust tube and leading-in wires of the mount are inserted in the mount support tube until the stem rests on the shoulder 23, the exhaust tube extending nearly to the. bottom of the pin. The lamp bulb is then placed over supported in proper relation thereto by the bulb support 15. I a

.As previously mentioned, the blocks 21 axially align the exhaust tube 2 of the mount in the mount support tube 18 and as well align the mount support tube 18 and the battle tube 19, the'fiange of the stem tube 1 of the mount resting on mount is thus vertically and horizontally aligned with the spindle. as. a whole. -The bulb support 15, axially spindle, serves to align the lamp bulb with respect to the spindle and may be varied vertically with respect thereto by adjusting the height of the support rods .15 in the upright supports 14. and looking into position the mount and isalinged with the with the set screws 15", or by adjusting the position of the bulb support 15 with respect to the support'rods 15. This arrangement of apparatus permits of a ready, accurate alignment or positioning of the filament in the lamp bulb whether the lamp bulb be made of clear glass, colored glass or a translucent glass such as opal glass.

The assembly of lamp parts previously described, takes place at position A. At positions B and C the head 12 is rotated while the gas jets'35 and 36, respectively, preliminarily heat that ortion of the bulb neck which is to be sealed to the mount. At position D, while the head is rotated, an intensive heating is given by the gas jets 37 and 38 suflicient to cause the bulb neck to fuse to the stem of the mount. At position E, while the head is rotated,

the gas jets 39 and 40 direct a sharp flame.

on the neck of the bulb at a point somewhat below theseal just made between the stem andneck. In this position, the lower end of the main support tube is in line but somewhat above an open'air pipe 41 (shown in "Fig. 6.) which is fastened to and passes through the bed of the machine and which is connected to a source of air pressure. Air emitted from the pipe 41 enters the main. support tube and passes upward through it to the lower chamber 27 of the baflie tube, striking the end of the mount support tube and the baffle upon leaving the upper end of the main support tube. From the chamber 27 the air passes the bafile by going throughfthe channels 29 into the upper chamber 26 and from herepasses through the openings 22 into the mount support tube. From the mount support tube the air is emitted through the openings 25, and also through the upper end of the mount support tube, to blow off the surplus neck by blowing out the fused portion until it becomes so thin as to separate, the sur lus neck falling down around the spindle. eated air in the lamp after the seal is formed may escape through. the opening 6 into the exhaust tube which conducts-it to the lower inner end of the mount support tube 18 from where it passes through the openings 20 and 30 out into the atmosphere. The head is permitted to stay in'this position for a short time after the separation in order to polish the seal.

Position F is a cooling position and here the head is not rotated. Through the gripping disc 32' the spindle is preferably drawn down slightly at this point in order to permit the stem to draw in the neck slightly .around the sealand form a better shaped neck for basing,

In position A, the lamp is removed andanother set of lamp What-we claim is-:

parts assembled. 1. The method of manufacturing an candescent electric lamp or other electrical device comprising a bulb and a filament or other conductoraccurately positioned therein which consists in assembling a bulband a mount carrying said filament or othercon ductor and having an exhaust tube extending therefrom and definitely disposed rela tively to said filament or other conductor, definitely positioning said bulb, positioning said mount in one direction by means engaging the sides of said, exhaust tube and in another direction by means otherwise engaging said mount andthen fusing together portions of said bulb and said mount to form a seal.

2. The method of manufacturing an incandescent electric lamp or other electrical device comprising a bulb and a filament or other conductor accurately positioned therein which consists in assembling a bulb and a mount carrying said filament or other coning therefrom and axially disposed relatively to the said filament or other conductor, causing said bulb to assume a definite position, positioning said mount transversely by means engaging the sides of said exhaust tube and longitudinally by means otherwise engaging said mount and then fusing together portions of saidbulb and said mount to form a seal.

3. The method of manufacturing an incandescent electric lamp or other electrical device comprising a bulb and a filament or other conductor accurately positioned therein, which consists in assembling a bulb and a mount carrying said filament or other conductor and having an exhaust tube extending therefrom and axially disposed relatively to the said filament or other conductor, positioning said bulb with its neck portion extending vertically, positioning said mount transversely of said bulb by means engaging the sides of the said exhaust tube and longitudinally by means otherwise engaging said mount and then fusing together a portion of said bulb neck and said mount to form a seal.

4. The method of manufacturing-- an incandescent electric lamp or other electrical device comprising a bulb and a filament or other conductor accurately positioned therein which consists in assembling a bulb and a mount comprising a stem tube having said filament or other conductor carried'thereby and definitely positioned relatively thereto and an exhaust tube extending from within said stem tube and definitely positioned relain, which consists 1n assembling a bulb and tending from within the 7 device comprising a nally by means engaging said -in, which consists of the neck of said bulb to said stem tube to form a seal. I 5. The method of manufacturing. an incandescent electric lamp or other electrical device comprising a bulb and a filament or other conductor accurately positioned therea mount comprising a stem tube carrying said filament or other conductor definitely positioned relatively thereto and having exsame and axially thereof an exhaust tube, definitely positioning said bulb, positioning saidmount trans versely of said bulb by means engaging the sides of the said exhaust tube and longitudistem tube and then fusing a portion of the neck of said bulb to said stem tube to form a seal. 6. The method of manufacturing an incandescent electric lamp or other electrical bulb and a filament or other conductor accurately positioned there.-

in assembling a bulb and a mount comprising a stem tube having said filament or other conductor accurately positioned relatively to the said stem tub'eand having an exhaust tube extending from within the same and axially thereof, definitely positioning said bulb with its neck extending vertically, positioning said mount transversely stem tube and longitudiing beyond said said stem tube and nally by means engaging then' fusing a portion of the neck of said bulb to said stem tube to form a seal. a

of .said bulb by means engag ing that portion of said exhaust tubeproyect- 7 The method of manufacturing an. i n' lamp or other electrical device comprising a'bulb and afilament or other conductor accurately positioned therein, which consists in assembling a bulb and a mountcomprising a flanged stem tube having said filament or other conductor accurately positioned" relatively to the said flanged stem tube and having an exhaust tube extending from within the same and axially thereof, definitely positioning said candescent electric bulb with its neck extending vertically, po-

sitioning said tube and transversely of said bulb by means mount longitudinally of said bulb by a rest for the flange ofsaid stem.

engaging that portion of said exhaust tube projecting beyond said stem tube and then fusing a portion of the said stem tubefiange to form a seal.

In witness whereof, we have hereunto set our hands this 30th day of'July 1920.

the neck of'said bulb to LORIS EDWI'N MITCHELL,

. ARTHUR JAMEs'w IT 

